Current-Voltage and Capacitance-Voltage characteristics of Pd Schottky diodes fabricated on ZnO grown along Zn-and O-faces

摘要

Temperature dependent current-voltage (I-V) and capacitance-voltage (C-V) measurements were utilized to understand the transport mechanism of Pd Schottky diodes fabricated on Zn-and O-faces of ZnO. From I-V measurements, in accordance with the thermionic emission mechanism theory, it was found that the series resistance Rs and the ideality factor n were strongly temperature dependent that decreased with increasing temperature for both the faces (Zn and O-face) of ZnO revealing that the thermionic emission is not the dominant process. The barrier height ф_B(I-V) increased with increasing temperature for both faces. The measured values of ideality factor, barrier height and series resistance for Zn-and O-faces at room temperature were 4.4, 0.60 eV, 217 Ω and 2.8, 0.49 eV, 251 Ω respectively. The capacitance-voltage (C-V) measurements were used to determine the doping concentration N_d, the built-in-potential V_(bi) , and the barrier height ф_B(C-V). The doping concentration was found to be decreased with increasing depth. The barrier height Φ_B(C-V) calculated for O-polar and Zn-polar faces decreases with increasing temperature. The values of barrier height ф_B(C-V) determined from C-V measurements were found higher than the values of barrier height ф_B(I-V).Keeping in view the calculated values of ideality factor, barrier height, and series resistance shows that O-polar face is qualitatively better than Zn-polar face.